31. Natural phenols Stacking, a chemical property of molecules with aromaticity , is seen occurring between phenolic molecules. 32. The quantum mechanical origins of this stability, or aromaticity , were first modelled by H�ckel in 1931. 33. Although PAHs clearly are aromatic compounds, the degree of aromaticity can be different for each ring segment. 34. Thiazoles are characterized by larger pi-electron delocalization than the corresponding oxazoles and have therefore greater aromaticity . 35. Biosynthesis of aromaticity is restored via the loss of a proton at the C ( 2 ) atom. 36. Independently of Jun-ichi Aihara, he introduced topological resonance energy as a reliable theory of aromaticity . 37. Metal aromaticity in metal clusters is another example of delocalization, this time often in three-dimensional entities. 38. Y-aromaticity is a concept developed to explain the extraordinary stability and high basicity of the guanidinium cation. 39. For residual fuel oil two other empirical indexes are used CII and Calculated Carbon Aromaticity Index ( CCAI ). 40. In organic chemistry, the term "'aromaticity "'is used to describe a reactivity ).
